Sadly yes. IANAL but under the Ripa Act they can issue a section 49 notice and you risk imprisonment for not complying. However, they need proper authorisation to do so, and the notice must be lawfully issued, so presumably a magistrate. This is all part of our famous British Justice!
There are several exceptions. Like border crossing or when hate crime is investigated. Arguing about legality, while interacting with police, is always losing move.
Just carry burner devices, and store sensitive stuff somewhere safe!
I agree! Having seen how some of the police operate in parts of Europe I wouldn't want to upset them especially if I don't speak the language. I have a burner tablet and can always keep stuff I need in the Cloud.